As is conventional, internal combustion engines typically use a cam shaft which operates on a finger follower or a push rod in order to open and close the valves of the cylinder. In order to minimize lash, the cams and the push rods or finger followers use a hydraulic element, conventional referred to as a hydraulic lash adjuster. In one typical arrangement, the hydraulic lash adjuster is positioned between the cam follower and the push rod/finger follower.
As is conventional, cylinders of internal combustion engines often have four or more valves. These valves are typically positioned in groups of two or more and can be operated simultaneously for either intake or exhaust. In such an engine, two or more hydraulic lash adjusters can be housed in a common housing which is operated on by a single cam. One end of the housing has a cam follower while the other end of the housing is open to allow for the push rods or the finger followers to mate with the hydraulic lash adjuster.
One of the problems faced in this field is the proper orientation of the hydraulic lash adjuster as well as preventing the rotation of the hydraulic lash adjuster as it is operated on by the cam. One solution to this problem is to modify the exterior housing of the lash adjuster either to provide a flat surface or to provide an axial groove an pin like arrangement between the outer housing of the lash adjuster and the bore in which the adjuster is housed. Conventional hydraulic lash adjusters have cylindrical outer housings which do not conventional contain flats, pins or grooves. Additionally, hydraulic lash adjusters generally have outer housings which are made of metal. Thus, it can be expensive to make special hydraulic lash adjusters and to maintain an inventory of hydraulic lash adjusters having the special designs.
There is a need to simplify the design employed for maintaining the orientation and preventing the rotation of the hydraulic lash adjusters.